Internet of Things (IoT) has posed new requirements to the underlying processing architecture, specially for real-time applications, such as event-detection services. Complex Event Processing (CEP) engines provide a powerful tool to implement these services. Fog computing has raised as a solution to support IoT real-time applications, in contrast to the Cloud-based approach. This work is aimed at analysing a CEP-based Fog architecture for real-time IoT applications that uses a publish-subscribe protocol. A testbed has been developed with low-cost and local resources to verify the suitability of CEP-engines to low-cost computing resources. To assess performance we have analysed the effectiveness and cost of the proposal in terms of latency and resource usage, respectively. Results show that the fog computing architecture reduces event-detection latencies up to 35%, while the available computing resources are being used more efficiently, when compared to a Cloud deployment. Performance evaluation also identifies the communication between the CEP-engine and the final users as the most time consuming component of latency. Moreover, the latency analysis concludes that the time required by CEP-engine is related to the compute resources, but is nonlinear dependent of the number of things connected.

中文翻译：

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基于CEP的实时物联网应用中雾和云计算的实验研究

物联网 (IoT) 对底层处理架构提出了新的要求，特别是对于实时应用程序，例如事件检测服务。复杂事件处理 (CEP) 引擎为实现这些服务提供了强大的工具。与基于云的方法相比，雾计算已成为支持物联网实时应用程序的解决方案。这项工作旨在为使用发布-订阅协议的实时物联网应用分析基于 CEP 的雾架构。使用低成本和本地资源开发了一个测试平台，以验证 CEP 引擎对低成本计算资源的适用性。为了评估性能，我们分别在延迟和资源使用方面分析了提案的有效性和成本。结果表明，与云部署相比，雾计算架构将事件检测延迟降低了 35%，同时更有效地使用了可用计算资源。性能评估还将 CEP 引擎与最终用户之间的通信确定为延迟中最耗时的部分。此外，延迟分析得出结论，CEP 引擎所需的时间与计算资源有关，但与连接的事物数量呈非线性相关。